Optimized kernel builds: the straight dope [fp extensions]

[Krzysztof Lichota]

John Richard Moser napisał(a):
> I've been told that using SSE (the SIMD floating point extension that
> Intel developed) takes ~17 cycles to load an SSE register because it's
> not standard IEEE 754 floats and thus has to be converted from the FPU
> registers.  Also the SIMDs are all floating point, it makes no sense to
> copy data back and forth like that; a MOV, MOVS, or MOVSB instruction
> would be faster and more appropriate.

MMX instructions were integer operations. SSE introduced floating-point
operations. SSE2 introduced integer operations on longer registers. See:
http://en.wikipedia.org/wiki/Streaming_SIMD_Extensions.
SIMD is just the name of generic type of instructions.

	Krzysztof Lichota

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